Abstract: A color display device based on dielectrophoresis is described. The device includes a dielectrophoretic mixture comprising semi-insulating particles of each of the subtractive primary colors cyan (32), magenta (34) and yellow (36) in a semi-insulating liquid (24). The dielectrophoretic frequency characteristics of the particles are the same or similar for particles of the same color but different between the three colors. In particular, the transition frequency (f0) is different for each color, or two colors may have the same transition frequency (f0) if one has a reversed sense dielectrophoretic frequency characteristic. Also the speeds of the particles are the same for particles of the same color but different between the three colors. The pixels are driven with alternating voltages of different frequencies (f1, f2, f3, f4) and duration determined such that different proportions of the different colors of particles are moved, dependent upon their transition frequencies and speeds.

Abstract: An active matrix display device of the kind having two terminal non-linear switching devices (15) such as thin film diodes connected in series with the electro-optic, e.g. LC, display elements (12) between associated row and column address conductors (16, 17), in which the display elements are driven using pulse width modulated data signals and a wide range of grey-scale levels is achieved by using selection signals whose form is determined such that the current flow through the switching devices upon selection is controlled in an appropriate manner. To this end, the selection signals can be shaped to provide a more constant charging level over the selection period.

Abstract: A color display device based on dielectrophoresis is described. The device includes a dielectrophoretic mixture comprising semi-insulating particles of each of the subtractive primary colors cyan (32), magenta (34) and yellow (36) in a semi-insulating liquid (24). The dielectrophoretic frequency characteristics of the particles are the same or similar for particles of the same color but different between the three colors. In particular, the transition frequency (f0) is different for each color, or two colors may have the same transition frequency (f0) if one has a reversed sense dielectrophoretic frequency characteristic. Also the speeds of the particles are the same for particles of the same color but different between the three colors. The pixels are driven with alternating voltages of different frequencies (f1, f2, f3, f4) and duration determined such that different proportions of the different colors of particles are moved, dependent upon their transition frequencies and speeds.

Abstract: A micromechanical switch (1) is disclosed together with a method of manufacturing the same. The micromechanical switch comprises a beam (13) at least partially suspended above a planar substrate (10); two control electrodes (12, 19), one of which is at least partially located above the beam (19) and the other is at least partially located below the beam (12), both in relation to the substrate; and at least one contact electrode (11, 18); wherein applying a potential at either one of the control electrodes generates an attractive force between that control electrode and a conductive portion of the beam (15, 17) whereby the beam is caused to deflect in a direction (25) perpendicular to the plane of the substrate; and wherein applying a potential to at least one of the control electrodes causes a conductive portion of the beam to contact the or one of the contact electrodes.

Abstract: An active matrix display device of the kind having two terminal non-linear switching devices (15) such as thin film diodes connected in series with the electro-optic, e.g. LC, display elements (12) between associated row and column address conductors (16, 17), in which the display elements are driven using pulse width modulated data signals and a wide range of grey-scale levels is achieved by using selection signals whose form is determined such that the current flow through the switching devices upon selection is controlled in an appropriate manner. To this end, the selection signals can be shaped to provide a more constant charging level over the selection period.

Abstract: An active matrix display device of the kind having two terminal non-linear switching devices (15) such as thin film diodes connected in series with the electro-optic, e.g. LC, display elements (12) between associated row and column address conductors (16, 17), in which the display elements are driven using pulse width modulated data signals and a wide range of grey-scale levels is achieved by using selection signals whose form is determined such that the current flow through the switching devices upon selection is controlled in an appropriate manner. To this end, the selection signals can be shaped to provide a more constant charging level the selection period.

Abstract: In an active matrix display device having an army of electro-optic, e.g. liquid crystal, display elements (12) which are each connected in series with a two-terminal non-linear device (15), such as a MIM type thin film diode, between associated row and column address conductors (16,17), and are driven by a circuit, (20,22) to produce a display effect by applying a selection signal to each row address conductor in turn and data signals to the column address conductors, a selection signal comprising a voltage pulse signal whose magnitude is increased gradually and in a controlled fashion to a maximum selection voltage amplitude is used so as to reduce the extent of ageing in the non-linear devices and differential ageing effects on display elements driven to different levels over a period of use by reducing peak currents flowing through the non-linear devices. The rising edge of the selection pulse signal is suitably shaped, for example by ramping or stepping, for this purpose.

Abstract: In operation of an active matrix display device comprising an array of display elements (12), for example liquid crystal elements, each connected in series with an associated two terminal non-linear switching device (30), e.g. a MIM, between row and column address conductors (22,24), and row and column driver circuits (40,43) for applying selection signals to each row conductor in turn and data signals to the column conductors, the data signals are applied for part only of the row address period and a row selection signal commences prior to the data signal and while a reference potential is applied to the column conductors whereby during a row address period a display element is initially charged to a level approaching the lower end of the display element's operational range of voltages and thereafter charged to the required level according to the data signal. Vertical cross-talk is reduced and peak current density through the non-linear devices is kept low, thereby avoiding the risk of damage.